Evaluating the multi-phase evolution of social-ecological system coordinated adaptability under water environmental constraints: A case study of Xiamen Island

During urban evolution, complex dynamic interactions occur both between the water-environmental system (WES) and the social-ecological system (SES) and between the human-socioeconomic subsystem (HSS) and the ecological-environmental subsystem (EES) within the SES. However, their evolutionary characteristics and feedback relationships remain insufficiently explored, limiting the clarity and effectiveness of environmental governance strategies. This study constructs a comprehensive dynamic evaluation framework that integrates methods such as cloud model, adaptive cycle theory model, and catastrophe theory models. It can identify the development phases of various subdistricts in the city, their phase-specific feedback and synergies, and reveal the nonlinear dynamic changes in coordinated adaptability. The results indicate that: (1) During the study period, the overall coordination adaptability followed the phase sequence of κ > γ > α > Ω, exhibiting significant spatial linkage and clustering, with a pattern of high peripheral and low central areas coexisting with high southern and low northern areas; (2) Based on the three-dimensional characteristics of coordinated adaptability, three types of subdistircts are identified, with their differing characteristics influenced by the interplay of internal and external systems; (3) Type A subdistricts mainly have insufficient per capita ecological resources, Type B subdistricts have low environmental efficiency and poor pollution control, and Type C subdistricts have limited ecological space, low environmental quality, and pollution accumulation; (4) Accordingly, identified key obstacle factors and proposed differentiated governance strategies, providing a reference for the refined formulation of sustainable development policies appropriate for Xiamen Island.